HST / Lickey Incline

[jimbob4life]

Does anyone know the specific instructions for a HST when climbing this?

 

[OneTrackMind]

In my head I can only imagine a face of Jeremy Clarkson shouting "Power!*".

*Unless there is poor adhesion of course.

 

[SkinnyDave]

This would be better shifted to Traction section of the foru
.

I would go for James Earl Jones sayin PPPowerrrr

 

[daikilo]

I would go for James Earl Jones sayin PPPowerrrr

This much power ...
https://www.youtube.com/watch?v=3rvEw6M3WtQ

As to instructions "respect the speed limits" (in both directions).

 

[70014IronDuke]

I have no specialist knowledge, but I would have expected an instruction for both power cars to be working. A single power car would surely risk stalling on the bank, certainly in the leaf-fall season?

 

[D1009]

I have no specialist knowledge, but I would have expected an instruction for both power cars to be working. A single power car would surely risk stalling on the bank, certainly in the leaf-fall season?

The rule used to be that an HST on one power car in normal rail conditions is allowed subject to having a clear run from Stoke Works Jn to Blackwell. I think something similar applied to other stock with more than a certain number of engines out. Whether it's any different now I have no idea.

 

[najaB]

The rule used to be that an HST on one power car in normal rail conditions is allowed subject to having a clear run from Stoke Works Jn to Blackwell.

That sounds reasonable - a similar rule applies for the up Highland Chieftain. It has to have a clear run to Schlod Summit and isn't allowed to restart forwards if it comes to a stand before reaching there.

 

[CC 72100]

Should be in the relevant sectional appendix - under special instructions

 

[najaB]

Should be in the relevant sectional appendix - under special instructions

Having a hunt through the SA as we speak (well, read).

It's on pages 55 - 56: Western Region Sectional Appendix.

 

[SpacePhoenix]

What would happen if the HST has been chasing single yellows all the way to Lickey, would it get terminated or would it get held at Stoke Works junction until it's greens all the way up Lickey and take it at full power?

 

[Phil.]

What would happen if the HST has been chasing single yellows all the way to Lickey, would it get terminated or would it get held at Stoke Works junction until it's greens all the way up Lickey and take it at full power?

Did you read D1009's post?

 

[najaB]

What would happen if the HST has been chasing single yellows all the way to Lickey, would it get terminated or would it get held at Stoke Works junction until it's greens all the way up Lickey and take it at full power?

Why would it be terminated?

 

[SpacePhoenix]

Why would it be terminated?

To avoid having a train blocking the mainline

 

[najaB]

To avoid having a train blocking the mainline

It wouldn't block the mainline with a clear run from Stoke Works Jn.

 

[D1009]

Having a hunt through the SA as we speak (well, read).

It's on pages 55 - 56: Western Region Sectional Appendix.

It wouldn't block the mainline with a clear run from Stoke Works Jn.

Thanks for posting that link which given the big file I couldn't be bothered to go into earlier, but good to see it updated with the new signal numbers. I got it a bit wrong in that it's actually Oddingley from which need a clear run, a bit further back than Stoke Works Jn.

I used to commute from Bristol Parkway to New Street, and can vaguely remember an occasion where we had only two engines running on a 5 car Voyager, and the train stopped somewhere before Stoke Works Jn to request a clear run.

 

[PHILIPE]

On occasions on GWR, the Totnes stop is omitted to enable the train to get a run up Rattery Bank if conditions doubtful

 

[daikilo]

Surely a single-engine HST could actually restart on the Lickey in near-zero wheel-slip conditions. May not go very fast to the top but the load is not that high.

 

[najaB]

Surely a single-engine HST could actually restart on the Lickey in near-zero wheel-slip conditions. May not go very fast to the top but the load is not that high.

It's probably possible, but the railway doesn't like 'probably'.

 

[Topgun333]

Two power cars and six mk3 carriages weigh about 350 tonnes. The Lickey Incline is 3.2km long with an average gradient of 1:37.5.

How far will a train progress up the incline if it approaches the incline at 160kph and switches its engine into neutral at the start of the ascent?

 

[AnonymousUser1]

To avoid having a train blocking the mainline

no it would be held as the signals the previous posters have mentioned until it has a sufficent run of green signals to make the bank safely.

 

[70014IronDuke]

Two power cars and six mk3 carriages weigh about 350 tonnes. The Lickey Incline is 3.2km long with an average gradient of 1:37.5.

How far will a train progress up the incline if it approaches the incline at 160kph and switches its engine into neutral at the start of the ascent?

The mass of the train is largely irrelevant.

I don't know what the rolling resistance is, but if there were no friction losses, I make it approximately 3.75 km. Obviously it would be significantly less than that due to friction losses, etc. (very roughly, the kinetic energy at 160 kmph would allow the train to rise roughly 100m) but I've probably forgotten how to do it and made a mistake. ) :cry:

 

[Class172]

I think something similar applied to other stock with more than a certain number of engines out. Whether it's any different now I have no idea.

If I recall 15x and 170s are subject to the rule also and must be running with at least 50% power. When this happens (in my experience), the call at Bromsgrove is cancelled to allow a suitable run-up from Stoke Works Jct. I don't know if this extends to 172s which have much better performance.

 

[najaB]

The mass of the train is largely irrelevant.

I would have thought the mass of the train is highly relevant: p = mv after all.

 

[Class172]

The easiest way to calculate it would be in terms of energy conservation such that GPE gained (height) = KE lost - Work done (against frictional losses). I haven't got any paper to hand, but that's how you'd do it.

mgh = 1/2 mv^2 - (mgμ*d)
m=mass
g=9.81ms^-2
h=height gained
v=velocity
μ=coefficient of friction
d=distance travelled

The angle incline is small enough that you can probably ignore the effect of angle.

 

[XDM]

I would have thought the mass of the train is highly relevant: p = mv after all.

The mass of the train is only relevant for the rolling resistance,which is far smaller than the work needed to draw the train up most gradients. For the main work, the HST's kinetic energy overcoming the energy needed to get the train as far up the hill as it can,the mass is on both sides of the equation. That is why it cancels out & is irrelevant. In a vacuum a feather & an HST fall at the same speed. The masses cancel out! Once air resistance is introduced, the feather is designed like a parachute & has massive air resistance in ratio to its weight & so it falls rather slower than the HST! Likey is not in a vacuum, so air resistance & the rolling resistance(it used to be said to be 5lbs a ton of train weight) come into play & will reduce the distance the train runs. I have probably bored the patience of everyone now. But 10 lbs a ton total air/rolling resistance is 3,500 lbs,compared with 350 x 2000/37.5 lbs = 18,000lbs of the hill climbing resistance. So I reckon the distance reached will be 35/180 less than the wise poster calculated. I would welcome being corrected,but with an understandable explanation.

 

[najaB]

Likey is not in a vacuum, so air resistance & the rolling resistance(it used to be said to be 5lbs a ton of train weight) come into play...

I knew steel wheel on steel rail was low, but never knew it was that low. In which case I agree the mass is more or less irrelevant.

 

[daikilo]

I knew steel wheel on steel rail was low, but never knew it was that low. In which case I agree the mass is more or less irrelevant.

That will be an average because air resistance (frontal area and skin) is certainly not a constant for all vehicles, the HST being particularly low (good).

 

[SpacePhoenix]

If an HST is running on a single working power car, does it make any difference as to if it's the front or rear power car with the working engine?

 

[najaB]

If an HST is running on a single working power car, does it make any difference as to if it's the front or rear power car with the working engine?

Difference in what regards? I would have thought that performance should be the same but, based on my extremely small sample size, the ride is jerkier when moving off from a stop with only the rear PC working.

 

[70014IronDuke]

I knew steel wheel on steel rail was low, but never knew it was that low. In which case I agree the mass is more or less irrelevant.

I don't think the rolling resistance is really due to the coefficient of friction between a moving steel wheel on rail - that is ridiculously low. Rather, it is the combination of frictional losses in the bearings and traction motor gears and the like. And induced electrical losses in the traction motors.

At 160 kmph there would be losses due to air resistance. Below about 60kmph this would become negligible.

But the key point I was making, however counter-intuitive, is the mass part of the kinetic energy of the train moving is countered by the mass part in the potential energy of the train as it ascends a gradient. So mass, in that sense, is irrelevant.